Genology
Chubby
Cby - Wild Type Dominant.Effect = None.
cby - Chubby, autosomal recessive.
Effect = Homozygotes have short limbs, short ears and move very slowly, death at about 35 days.
Veterinarian Resources; Stock and Strain List http://www.nih.gov/od/ors/dirs/vrp/s&slst.htm#ratinbred.
Dumbo Eared
Also known as "Japanese Elphant Eared". Ive yet to find any scientific literature on dumbo eared rats as we have them in USA fancy, and the symbol assigned here is simply one Ive seen more than a few breeders use for an abreviation. It does breed recessive and it "exists" since we breed and show them (rather unmistakable!), but confirmation in scientific literature which would identify a proper symbol, additional alleles, associatied health aspects etc. has yet to be found (by me). The closest I found was a similar ear and skull reference is association to recessive cateracts. Whether or not Recessive Cateract, rc is related to du or not (perhaps a milder allele), Ive no idea, but the dumbos bred for fancy are not known to have any tendancy towards cateracts.Du - Wildtype Dominant.
Effect = None.
du - Dumbo, recessive.
Effect = Dumbo rats have larger, lowerset ears and a somewhat flattened, broader skull.
Dwarfism
Dw1 - Wild Type Dominant.Effect = None.
dw1 - Dwarfism.
Effect = Dwarfism
Dwarfism 1
Dw1 - Wild Type Dominant.Effect = None.
dw1 - Dwarfism, recessive.
Effect = By age 5 days dwarfs are noticeably smaller, by age 12 days, significantly so. Fur is softer and finer/thinner on the dwarfs and this lasts through adulthood. Both genders Steril, and testes on males remain small even in adulthood and the males remain about the same size as females throughout life (normally males are slightly larger). Size of a dwarf adult is about 70% that of a normal female.
Veterinarian Resources; Robinson, Roy. Genetics of the Norway Rat Pergamun Press 1965. pg 54
Dwarfism 2
Dw2 - Wild Type Dominant.Effect = None.
dw2 - Dwarfism, recessive.
Effect = significant size difference becomes apparent by the 2nd month of age. they often have bulging eyes (exophthalmos). Artificial tears may be needed in some case to lubricate the eye(s). Males steril but females are fertile.
Veterinarian Resources; Robinson, Roy. Genetics of the Norway Rat Pergamun Press 1965. pg 55
Dwarfism 3
Located on Chromosome #20Dw3 - Wild Type Dominant.
Effect = None
dw3 - Dwarfism, recessive.
Effect = Male are usually steril; females are fertile but dont reproduce well. The loci controlling the body size and fertility are linked to the major histocompatibility complex (MHC) as part of the the growth and reproduction complex (Grc). The recessive gene influencing fertility is symbolized 'f'. The map distance between the Grc and the MHC is 0.6 cM. T. J. Gill III and H. W. Kunz Gene complex controlling growth and fertility linked to the major histocompability complex in the rat.
Veterinarian Resources; Amer. J. Pathol. Volume: 96 Pages: 185-202 Year: 1979
H. W. Kunz, T. J. Gill III, B. D. Dixon, F. H. Taylor and D. L. Greiner Growth and reproduction comples in the rat. Genes linked to the major histocompatibility complex that affect development Journal: J. Exp. Med Volume: 152 Pages: 1506-1518 Year: 1980
Dwarfism 4
Dw4 - Wild Type Dominant.Effect = None.
dw4 - Dwarfism.
Effect = Possible additional form of dwarfism that might exist in american fancy lines. I am not certain, but it appears to be a simple recessive. Males are about 2/3rds the size of normal males and females are about 1/2 size of normal females. Affected animals are fertile and females have no laboring problems (at least, not to date). No health problems have been seen in affected animals either.
Hypodactyly
Located on Chromosome #5, Linked to Incisorless Hd - WildType Dominant.Effect = None.
hd - Hypodactyl Recessive.
Effect = Affected rats have fewer than normal toes, usually on the back feet. the usual number of toes is 3. Females are fertile but males are steril.
Veterinarian Resources; Robinson, Roy. Genetics of the Norway Rat. Pergamun Press 1965. pg 230.
Moutier R. Linkage of the hypodactyly and incisorless genes in the Norway rat. Journal of Heredity. 1980 Mar; 71(2): 129-130.
Incisorless
Located on Chromosome #5, linked to Hypodactyly. In - WildType Dominant.Effect = None.
in - Incisorless recessive.
Effect = Affected rats lack teeth as they never erupt...they tend to grow slower than their siblings but eventually reach full size. This may include a delay in the onset of pueberty.
Veterinarian Resources; Moutier R. Linkage of the hypodactyly and incisorless genes in the Norway rat. Journal of Heredity. 1980 Mar; 71(2): 129-130.
Robinson, Roy. Genetics of the Norway Rat. Pergamun Press 1965. pp 235.
Leptin Receptor
Located on Chromosome #5 Lepr - Wild Type Dominant.Effect = None.
lepr(cp) - Fatty Corpulent recessive.
Effect = Overweight and usually develop diabetes. Recognized 4-5 weeks of age; mature weights 800-1000 gm. Genes in Overweight Mice, Rats Carry Instructions for Leptin Receptor. http://www.rockefeller.edu/pubinfo/db-fa_genes.nr.html
Veterinarian Resources; Stock and Strain List http://www.nih.gov/od/ors/dirs/vrp/s&slst.htm#ratinbred.
Truett, G. E. et Al. Rat obesity gene fatty (fa) maps to chromosome 5: Evidence for homology with the mouse gene diabetes (db)Proc. Natl. Acad. Sci. USAVolume: 88Pages: 7806-7809Year: 1991
Recessive Cateract
Rc - Wild Type Dominant.Effect = None.
rc - Recessive Cateract recessive.
Effect = Lens change is present at birth and non-progressive but expresses asymmetrically between the two eyes; skull is somewhat flattened and ears set lower on the side of the skull than normal.
Veterinarian Resources; Stock and Strain List http://www.nih.gov/od/ors/dirs/vrp/s&slst.htm#ratinbred.
Skinny Locus
Sk - Wild Type Dominant.Effect = None.
sk - Skinny recessive.
Effect = Sigicantly reduced body size often accompanied by bulging skull.
Veterinarian Resources; Stock and Strain List http://www.nih.gov/od/ors/dirs/vrp/s&slst.htm#ratinbred.
Stub Tail
Located on Chromosome #4, near Kinky (coat type). St - Wild Type Stub tail.Effect = None.
st - stub tail recessive.
Effect = A mutation affecting tail length, lethal in homozygous form (death at or shortly after birth; a very few manage to survive to adult hood). It is similar to Tal phenotypically. Its also linked to "kinky" a recessive hair mutation. Stub, is likely extinct in the scientific world.
Common disorders in the rats that did not survive include: pelvic bone incompletely formed, distorted, displaced). Hind Limbs (various degrees of fused bones and/or misformed muscle). Hypoplasia and less commonly aplasia of intesinal and genitourinary tracts. Aplastic colon, rectum, anus. Abnormally formed or missing kidnies, ureters, bladder, urethra. Common health problems of surviving rats include: (note: in most of these tail length varied from as long as 5cm shorter than normal to a stubby 4cm (approx) long tail): Vertebrae twisted and/or curled. Toes on the feet maybe hypoplastic (in some cases totally missing toes). Kidneys sometimes inflamed or not fully functional. Reduced bodyweight (about 72% for males and 67% for females). Reduction in size of male's testes and females overies. Irregular oestrous cycle in females.
Veterinarian Resources; DJ Schaid, HW Kunz and TJ Gill 3d Genetic interaction causing embryonic mortality in the rat: epistasis between the Tal and grc genes . Genetics, Vol 100, 615-632. (Breifly compairs Tal to Stub on Page 628).
Robinson, Roy. Genetics of the Norway Rat Pergamun Press 1965. Pg 223-224.
Tail Anomoly Locus
Located on Chromosome #1 Tal - Taillessness Dominant.Effect = Lethal, "tail anomaly" is lethal when homozygous but when heterozygous. It causes kinks and reduced length to the tail, in addition to reduced body weight. It is incompletely penetrant and has variable expressivity, which is influenced partly by its genetic background.
tal - WildType Recessive.
Effect = None.
Veterinarian Resources; Schaid DJ, Kunz HW, Gill TJ 3d. Genic interaction causing embryonic mortality in the rat: epistasis between the Tal and grc genes. Genetics1982 Apr;100(4):615-632.
Morriss-Kay, G.M. and S. V. Hunt. Preliminary characterization of a skeletal mutant, Tal-2, and a comment on linkage group I to which it maps Rat News Letter Volume: 5 Pages: 6-7 Year: 1986.
Gill TJ 3d, Siew S, Kunz HW. Major histocompatibility complex (MHC)-linked genes affecting development. Journal of Experimental Zoology 1983 Nov;228(2):325-345.
Stock and Strain List http://www.nih.gov/od/ors/dirs/vrp/s&slst.htm#ratinbred.
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